Graphic method for reporting risk to a patient

ABSTRACT

A graph comprising a distribution curve for displaying a distribution of test results for given population and a density gradient superimposed over the distribution curve for displaying and probability of an event or condition occurring for each such test result in the distribution. Typically the distribution curve is plotted against a cartesian coordinate system. The density gradient is superimposed below the distribution curve and shows the increasing risk of a condition as a function of a test result by an increase in density of the gradient with increasing risk. A marker imposed on the distribution curve shows the test result for a specific individual.

This is a continuation of application Ser. No. 07/272,084, filed Nov.16, 1988, now U.S. Pat. No. 5,037,305, granted Aug. 6, 1991.

FIELD OF THE INVENTION

This invention relates to the field of charts and graphs for reportingtest results to a patient and more specifically a graph forsimultaneously reporting to a patient the results of a test, thenormalcy of that test result and the risk of an event occurring based onthat test result.

BACKGROUND OF THE INVENTION

The world, and particularly the medical world, is primarily one ofprobabilities. For example, a patient contemplating a heart transplantcannot be told whether or not he will survive, but only the statisticalprobability that he will survive. Similarly, a patient consideringtaking a medication, cannot be told that the medication is effective,but only that it is, for example, 80% effective or 20% effective. Thisuncertainty is particularly disconcerting in diagnostic testing.

For example, expectant mothers are often tested for the level ofalphafetoprotein in their blood. If the level of the protein is high, itis likely that the fetus has a neural tube defect. If the level of theprotein is low, it is likely that the fetus has Down Syndrome. The test,however, is not certain. Again, the level of the protein is used only toindicate the statistical probability or risk that the fetus has one ofthe above mentioned conditions.

Currently, statistical probabilities regarding risk are not alwaysconveyed to the patient clearly. Many health care professionals usethreshold probabilities upon which they base their advice. If a riskexceeds a chosen threshold, they make a recommendation, e.g., a remedyto reduce or eliminate the risk or a test to more accurately determinethe risk. If the risk is below the threshold then the recommendation,e.g., remedy or test, is not made. The use of a threshold value alone,however, provides no indication of how the risk increases or decreasesabove or below that threshold. Thus, the use of a threshold-basedrecommendation provides little information for the patient toindependently determine whether to undergo a recommended remedy or test.

As an illustration, if the level of alphafetoprotein in the blood of anexpectant mother is below a threshold level, a physician may recommendthat an amniocentesis be performed to determine whether, in fact, thefetus has Down Syndrome. If the level is above the threshold level, anamniocentesis is not recommended. What is not told to the patient iswhether the risk changes substantially above or below that thresholdlevel. Depending on that change, and on the patient's aversion toamniocentesis or concern over Down Syndrome, an expectant mother whoselevel of alphafetoprotein is above the threshold level may still decideto accept the risks associated with amniocentesis and undergo thatprocedure. Likewise, an expectant mother whose alphafetoprotein level isbelow the threshold may nevertheless decide not to undergo therecommended amniocentesis procedure.

Accordingly, there is a need for a means to clearly indicate to thepatient the results of a particular test and the risk associated withthat test result together with information indicating whether the resultis a normal one and how the risk changes as the result changes. Thepatient can then make an informed decision on how to proceed. He can usethe knowledge of the risk together with his own concern regarding theremedy or further testing to make the decision which is best for him.

The invention is a method of displaying the results of testing maternalblood serum of a patient for alphafetoprotein level. Specifically, adistribution curve of alphafetoprotein levels in maternal blood serumfor a population of patients is represented on a surface in cartesiancoordinates, such that the distribution curve represents the number ofexpectant mothers on the vertical axis and the alphafetoprotein level onthe horizontal axis. A gradually changing risk, increasing for DownSyndrome and decreasing for Open Spina Bifida, with decreasingalphafetoprotein levels is represented on the surface along thehorizontal axis. A mark representing the alphafetoprotein level of thepatient being tested is placed on the surface. The risk of Down Syndromeand/or Open Spina Bifida to the patient is displayed at the mark by therepresentation of risk along the horizontal axis. As a result, thepatient is more easily able to assess the risk of abnormality than byprior AFP reporting techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a graph displaying the distribution of an indicator,alphafetoprotein concentration, within a population, expectant mothers.

FIG. 2 shows an overlay displaying the risk of a condition, DownSyndrome in the fetus, associated with the indicator used in FIG. 1 as adensity gradient.

FIG. 3 shows the overlay of FIG. 2 superimposed on the graph of FIG. 1according to the present invention.

FIG. 4 shows an overlay displaying the risk of a condition, spina bifidain the fetus, associated with the indicator used in FIG. 1 as a densitygradient.

FIG. 5 shows the overlays of FIGS. 2 and 4 superimposed on the graph ofFIG. 1 according to the present invention.

DETAILED DESCRIPTION

The graphs of the present invention are particularly applicable forreporting to expectant mothers the risk of their child being born witheither Down Syndrome or spina bifida. The risk of both conditions isdetermined statistically on the basis of the amount of alphafetoproteinmeasured in the expectant mother's blood.

FIG. 1 shows a graph 10 or chart according to the present inventionshowing the results of blood tests for alphafetoprotein of expectantmothers. The graph is based on a cartesian coordinate system with ahorizontal and a vertical axis 12, 14. The amount of alphafetoproteindetected in blood tests of expectant women is depicted on the horizontalaxis 12. The number of expectant mothers having a specific amount ofalphafetoprotein detected in a blood test is indicated on the verticalaxis 14.

The distribution curve 16 plotted against the two axes 12, 14 is, inthis case, in the shape of a bell curve. The curve indicates thedistribution of different alphafetoprotein concentrations found in bloodsamples. The largest number of expectant mothers had a level ofalphafetoproteins corresponding to the peak 18 of the bell curve. Noexpectant mothers had a tested concentration of alphafetoproteins lowerthan the left end 20 of the curve nor higher than the right end 22 ofthe curve. For purposes of illustration, the levels of alphafetoproteinwhich are considered normal by most physicians are the levels betweenthe normal minimum line 24 and the normal maximum line 26.

The normalcy lines 24, 26 represent the levels beyond which a physicianis likely to recommend further testing. The information used to draw thedistribution curve is obtained by compiling test results from apopulation of tested expectant mothers. The tested population mayconsist of all tested expectant mothers or a selected sample group. Thesample group may be chosen either to reflect the test resultsanticipated for a large population or for a specialized population with,for example, a specific range of ages or geographical affiliations.

The graph 10 is used to report an individual expectant mother's testresults. Such test results can be displayed by a vertical marker 28,which extends through the point on the horizontal axis 12 correspondingto the alphafetoprotein concentration detected in the expectant mother'sblood. A second vertical marker 29 displays a different test result fora second individual. Any number of .individual test results may beindicated. However, it is preferred that the test results of only oneperson be shown so that the test results remain confidential.

Looking at the graph 10, the individual can immediately see how closeher test result is to the prevailing norm and how close her test resultis to the accepted normal limits 24, 26. The graph 10 may besupplemented with information on averages, medians and standarddeviations. The average and median values could be displayed, forexample, using additional vertical markers. The accuracy of theindividual's test results, commonly expressed as plus or minus a certainfraction of the value obtained, could be expressed using the width ofthe vertical marker 28.

FIG. 2 shows an overlay 30 which may be placed over the graph 10 ofFIG. 1. For ease of interpretation, the overlay 30 preferably uses thesame distribution curve 16 plotted against the same horizontal andvertical axes 12, 14. Preferably, the graph 10 is drawn on an opaquesheet and the overlay 30 is drawn on a transparent sheet so that thedetails of the graph 10 can be seen through the transparent sheet 30when the overlay 30 is placed over the graph 10.

The alphafetoprotein concentration level in the blood of an expectantmother is used as an indicator for the risk of the child being born withDown Syndrome. The lower the alphafetoprotein level, the greater thechance that the child will have Down Syndrome. This information can bevaluable to a mother considering whether to undergo an amniocentesisprocedure.

The overlay 30 of FIG. 2 is designed to indicate the risk of the childbeing born with Down Syndrome. That risk is shown by a gradual densitygradient along the horizontal axis and below the distribution curve. Asthe level of alphafetoprotein decreases, the risk of bearing a childwith Down Syndrome increases, which is shown by an increase in thedensity of the gradient. It is understood that the density gradient isnot related to the vertical axis 14 and could, therefore, extend abovethe distribution curve, if desired. The ratios below the horizontal axis12 indicate the risk numerically.

The overlay 30, as depicted in FIG. 2, is placed over the graph 10 ofFIG. 1 to provide the tested individual with the additional risk-relatedinformation of FIG. 2, as shown in FIG. 3. By looking at the graph 10together with the overlay 30 as shown in FIG. 3, the individual caneasily compare her test results to the general distribution shown by thecurve 16 and at the same time to the level of risk that her child willbe born with Down Syndrome. An individual with test results similar tothose shown by the marker 28 substantially above the threshold marker24, in FIG. 3 could quickly conclude that her results were well withinnormal limits and the risk of Down Syndrome was less than it is formost. An individual with test results indicated by marker 29, stillabove the threshold level, but only slightly so, may conclude that thereis not an appreciable difference in risk between her indicated level anda level just below the threshold level. If so, she may conclude thatfurther testing, e.g. amniocentesis, is warranted.

The presentation of FIG. 3 may be produced either by laying atransparent sheet containing the density gradient 32 over an opaquesheet containing the graph 10 or by combining the graph 10 and overlay30 to form a single graph on a single sheet. Alternatively, thepresentation of FIG. 3 may be obtained by laying a transparent sheetcontaining the graph 10 over an opaque sheet containing the densitygradient 32.

Alphafetoprotein levels in expectant mothers are also used as anindicator to estimate the risk that a child will be born with a neuraltube defect, i.e. spina bifida. FIG. 4 shows on overlay 34 similar tothat of FIG. 2 which shows the spina bifida risk using a densitygradient 36. The risk decreases along the horizontal axis towards theorigin and the density lessens accordingly. As with FIG. 2, the verticalaxis is not related to the density gradient. Again, the ratios below thehorizontal axis 12 indicate the risk numerically. The overlay 34 of FIG.3 can be placed over the graph 10 of FIG. 1 either alone or togetherwith the overlay 30 of FIG. 2.

In FIG. 5 the two overlays 30, 34 have been combined with the graph 10of FIG. 1. This can be done either by laying both overlays 30, 34 overthe graph 10 or by producing a new graph depicting the information inboth overlays 30, 34 and the old graph 10. By looking at a graph similarto FIG. 5 the individual can compare her test results with those of thepopulation, and assess the risk of both Down Syndrome and spina bifidaall at the same time. This allows her to make a more educated judgmentmore quickly as to how to proceed than was possible previously.

In a preferred embodiment, the overlays are printed on transparentsheets and the density gradients of the overlays are different colors.For example, the density gradient for Down Syndrome could be red and thedensity gradient for spina bifida could be blue. The underlying graphcorresponding to graph 10 of FIG. 1 is preferably printed on an opaquesheet so that the markers and normalcy lines show clearly through thetransparent sheets. White is preferred for the background so that thedensity gradients are more clearly seen. Accordingly, both risks may beevaluated independently but form the same presentation.

The combination of graphs and overlays can be used to convey a greatvariety of data. Presently, it is preferred for use with medical testresults and may be adapted for a wide variety of tests. For example,cholesterol level is often measured to assess the risk of heart attack.The bell shaped curve 16 of FIG. 1, could easily be adapted to show thedistribution of cholesterol levels in a population. The population couldbe a large one, e.g. all adults, or a narrower one, e.g. smokers inNorth Dakota between 30 and 40 years of age. The marker again would showthe measured cholesterol level for a particular individual and theoverlays would show the risk of heart attack as a density gradient.

Other types of data may also be presented. For example, the chart couldplot admission test scores along the horizontal axis against the numberobtaining that score on the vertical axis for all test takers or fortakers on a particular date or in a particular geographic area. Theoverlays could then be used to show the likelihood of gainingadmittance. If the admittance test was a nationwide exam like the SAT(Scholastic Aptitude Test) or GRE (Graduate Record Exam), differentoverlays could be prepared for different schools. The individual, byplacing different overlays over the chart, could easily judge hischances for admittance at different schools.

The graphs of the present invention are useful for the presentation ofall types of data, provided that there is a distribution of values for agiven population and a statistical probability of an event occurring foreach such value. The exemplary embodiments herein all use a cartesiancoordinate system which is presently preferred for the informationdepicted. However, it is apparent that, for example, a polar coordinatesystem may be used in some cases. It is also apparent that, for example,a bar graph may be used to depict the distribution curve.

The invention is particularly well suited for computer printing. In amedical lab test environment a computer could store a variety ofdistribution curves and shading overlays for different risk groups. Whena test result is obtained, the computer could then select theappropriate distribution curve, apply the appropriate overlay and drawthe markers indicating the test result. Personalized reports could beprovided quickly and easily. The results may also be displayed on acomputer monitor directly.

It will be understood that a great variety of modifications andadaptations may be made to the present invention without departing fromits spirit and scope. By only showing a few exemplary embodiments theinventor does not intend to abandon these variations.

What is claimed is:
 1. A method of displaying the results of testingmaternal blood serum of a patient for alphafetoprotein level, the methodcomprising the steps of:representing on a surface in Cartesiancoordinates a distribution curve of alphafetoprotein levels in maternalblood serum for a population of patients such that the distributioncurve represents the number of expectant mothers on the vertical axisand the alphafetoprotein level on the horizontal axis; representing onthe surface a gradually increasing risk of Down Syndrome with decreasingalphafetoprotein levels along the horizontal axis; and placing on thesurface a mark representing the alphafetoprotein level of the patientbeing tested, and thus the risk of Down Syndrome to the patient by therepresentation of risk along the horizontal axis at the mark.
 2. Themethod of claim 1 in which the distribution curve represents increasingalphafetoprotein level from left-to-right on the surface and the riskrepresented along the horizontal axis decreases from left-to-right in amanner that represents the risk of Down Syndrome.
 3. The method of claim2, additionally comprising the step of representing on the surface agradually increasing risk of Open Spina Bifida with increasing levels ofalphafetoprotein on the horizontal axis.
 4. The method of claim 1,additionally comprising the step of representing on the surface agradually increasing risk of Open Spina Bifida with increasing levels ofalphafetoprotein on the horizontal axis.
 5. A method of displaying theresults of testing material blood serum of a patient foralphafetoprotein level, the method comprising the steps of:representingon a surface in cartesian coordinates a distribution curve ofalphafetoprotein levels in maternal blood serum for a population ofpatients such that the distribution curve represents the number ofexpectant mothers on the vertical axis and the alphafetoprotein level onthe horizontal axis; representing on the surface a gradually increasingrisk of Open Spina Bifida with increasing alphafetoprotein levels alongthe horizontal axis; and placing on the surface a mark representing thealphafetoprotein level of the patient being tested, and thus the risk ofOpen Spina Bifida to the patient by the representation of risk along thehorizontal axis at the mark.
 6. The method of claim 5 in which thedistribution curve represents increasing alphafetoprotein level fromleft-to-right on the surface and the risk represented along thehorizontal axis increases from left-to-right in a manner that representsthe risk of Open Spina Bifida.